It is known that an organic matter such as heavy oil sludges, cutting oils or textile oils, exists in water, microorganisms such as gram positive bacteria, gram negative bacteria, yeast or fungi in water degrade or denature the organic matter, producing various problems. For example, slime generates on a heat exchanger surface in circulating water cooling systems and in the cooling drainpipe in petrochemical and chemical and chemical plants, blocking up said pipe and thereby causing significant decreases in cooling capacity. Moreover, microorganisms such as gram positive bacteria, gram negative bacteria, yeast or fungi generated in white water in papermaking plants grow and product slime. When the slimes exfoliate and get mixed in paper products, they cause such various troubles as that the paper is used to break, stains spotwise and smells in the paper-rolling process.
Japanese Patent Examined Publication (Kokoku) No. 14294/1977 discloses that 4,5-dichloro-1,2-dithiol-3-one of the formula: ##STR1## (hereinafter sometimes referred to as "dithiol compound") is effective in preventing slime formation caused by microorganisms such as gram positive bacteria, gram negative bacteria, yeast or fungi in industrial water systems, particularly, in process water systems in paper mills and in cooling water systems, and the dithiol compound has already been put into practical use.
The dithiol compound itself exerts simultaneously and instantaneously the microbicidal effects when added to the water system. However, the dithiol compound is apt to decompose thereafter, and does not always exhibit long-lasting microbicidal activity. Therefore, it is unpractical to use the dithiol compound alone. Further, since the dithiol compound is a relatively expensive agent, it is desirable to use in an amount as small as possible.
The microbicidal/microbistatic agents for industrial use are generally toxic to human beings and animals, and cause environmental pollution by contaminating waste matter. Therefore, it has recently been required that such agents be used at a concentration as low as possible.
Accordingly, it has been attempted to decrease the amount of the dithiol compound and exhibit a synergistic effect by a combination of 4,5-dichloro-1,2-dithiol-3-one with bis(tribromomethyl) sulfone (Japanese Patent Examined Publication (Kokoku) No. 16084/1982), 2-bromo-2-nitropropane-1,3-diol (Japanese Patent Examined Publication (Kokoku) No. 42603/1982), haloacetic acid esters (U.S. Pat. No. 4,647,577), alkylene bisthiocyanates (U.S. Pat. No. 4,518,610), 1,2-benzisothiazolin-3-one (U.S. Pat. No. 4,466,975), isothiazolone salts (Japanese Patent Unexamined Publication (Kokai) No. 1105/1985) or dibromonitrilopropionamide (U.S. Pat. No. 4,879,306).
On the other hand, British Patent Publication No. 1091049/1968 discloses that N-dodecylguanidine hydrochloride is usable in a microbistatic paper and Japanese Patent Unexamined Publication (Kokai) No. 76867/1977 discloses a method of preventing industrial materials and other materials and articles from microbe-caused troubles by using films and sheets containing N-dodecylguanidine hydrochloride.
As mentioned above, various attempts have been made to develop microbicidal/microbistatic compositions capable of exhibiting patent and long-lasting microbicidal/microbistatic effects and achieve a decrease of the amount of the dithiol compound. However, it is still desired to develop an improved microbicidal/microbistatic composition for industrial use containing the dithiol compound.